The primary objective of this proposal is to make further progress towards an understanding of the function of pancreatic somatostatin. Changes in pancreatic somatostatin concentration in experimental diabetes will be studied both by radioimmunoassay and quantitative morphometry. The factors influencing the secretion of somatostatin will be determined by direct study using as models isolated islets, monolayer cultures of neonatal rat and chicken pancreas and the isolated perfused pancreas. The physiological role of somatostatin on insulin and glucagon regulation in the rat will be determined by means of passive immunization with antiserum to somatostatin. Studies of somatostatin biosynthesis will be undertaken in monolayer cultures of rat and chicken pancreas.